Impact resistance of ETICS – the role of the redispersible polymer powder

R. Raso1, T. Bühler1, V. Steinbauer2, T. Aberle3, H. Waser3, U. Heini3, J. Lang3
1University of Applied Sciences FHNW, Muttenz, CH
2University of Bern, CH
3Nouryon Chemicals AG, Sempach Station, CH

New research findings provide better understanding of the mechanical impact behavior of ETICS (External Thermal Insulation Composite Systems). The study was focused on dry mortar based systems, where the RPP (Redispersible Polymer Powder), contained in thebase coat, plays a key role beside many more influencing factors.
Type and amount of RPP decide on the adhesion to the insulation board and the polymer coated glass fiber mesh and on the cohesion and flexibility of the base coat. Thus, the RPP is responsible to allow the multi-layer system to act as one composite system, where the single parts contribute to the overall impact performance.
A precondition to achieve good mechanical impact resistance is an optimized workability and good Open Time of the base coat. These fresh mortar properties are often underestimated when products are developed on laboratory scale. However, on construction site under changing environmental conditions they are most critical for the long term impact performance of ETICS.